Vertical line, subscript x=a

Question

How do I write this formula in latex?

I tried this:

\big(f(x,b)\big)'_x|_{x=a}

but the result is different from what I want (the line is shorter).

I understand that this is probably a simple question but I can't find the answer probably because I can't find good words for the search

For a pretty exhaustive discussion, also see https://tex.stackexchange.com/q/294499/158639 . — chsk, May 05 '21 at 07:32

score 2 · Accepted Answer · answered May 05 '21 at 06:36

2

As posted in comments by user241266, the correct thing to do is

\left.\bigl(f(x,b)\bigr)'_x\right|_{x=a}

answered May 05 '21 at 06:36

gmvh

score 1 · Answer 2 · answered May 05 '21 at 08:28

1

You probably want something like

\documentclass{article}
\usepackage{amsmath}
\begin{document}
[
\bigl(f(x,b)\bigr)'x\Big|{x=a}
]
\end{document}

answered May 05 '21 at 08:28

egreg

2 Answers2